1. Field of the Invention
The present invention relates to computer networks and digital rights management. More specifically, it relates to sharing content on various devices and platforms having different digital rights management systems, in a network or domain.
2. Description of the Related Art
It is becoming increasingly common for users of a wide range of devices, ranging from MP3 players to hospital equipment, to want to share content with other users using different types of devices. The range of scenarios in which sharing or portability of content among devices in a defined domain or network is varied. One example is the home environment. In this domain, devices such as cell phones, MP3 players, PCs, and game consoles play different types of audio/visual or multimedia content. Family members in the home environment may want to play music that was originally downloaded and licensed for execution on an MP3 player on a cell phone or a PC instead. In another example, a family member who downloaded a movie onto a PC and obtained a license to play the movie on that PC may want to watch the movie on a cell phone in the home domain. Similar scenarios may occur in other settings, such as in a corporation or a hospital, in which media that was downloaded or installed on a specific device may need to be rendered or executed on another device within the same network or domain. For example, a doctor may want to play a clip of a medical video on her hand-held device that was originally downloaded onto a nurse's desktop workstation.
However, issues arise when users attempt to share content on different devices and platforms. In many cases it is not possible because of mismatches between digital rights management (DRM) systems associated with the content and DRM systems that are recognized by the devices. For example, if a song is downloaded onto an MP3 player, the user typically obtains a license token from the content provider to play that song on that MP3 player. If the user wants to play the song on a cell phone, the user must obtain a license allowing such usage. However, the cell phone and MP3 player typically have different native DRM systems. Thus, the DRM system on the cell phone would not know how to process or recognize the file representing the licensed song. Conflicts in DRM headers, methods of packaging content in a file format (e.g., different encryption schemes), metadata, and other factors, between the DRM system of the MP3 player and the DRM system of the cell phone would prevent sharing of the content.
The DRM system on one device does not how to read or open the license file for the content intended originally for a different DRM system. The format and encoding of the content file and the license are typically incompatible and foreign to one another, even if the content provider allows or has no legal objections to the content being rendered on different devices in the same domain. For example, the provider providing a song for an MP3 player may include in its license the right to the downloader to play the song on other devices in the user's same domain. Using the home environment as an example, the provider may not mind that the song be played by other household members on other devices in the home as long as one license is paid for by at least one member of the household. However, from a technical and DRM system standpoint, this is not always feasible. It may be possible with mapping of file formats or the establishment of secure communication channels (requiring some form of “handshake”) within devices in a domain and obtaining licenses from different sources, but this is not a practical solution since it requires significant additional steps, both technical and legal, be taken by the users and imposes additional processing burdens on the devices.